Changeover mechanism for motion picture machines



1934- I. H. CRABTREE 1,980,167

CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, 1929 6 Sheets-Sheet l INVENTOR 1mm 05957555 ATTORNEY NOV. 13, 1934. H, CRABTREE 1,980,167

CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, "1929 6 Sheets-Sheet 2 v NTOR IVORY/L1? mwreeg ATTORNEY Nov. 13, 1934. l. H. CRABTREE I 1,980,167

CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, 1929 6 Sheets-Sheet 3 ATTORNEY Nov. 13, 1934. 1. H. CRABTREE CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, 1929 6 Sheets-Sheet 4 INVENTOR lvom H Ci-THBT/Rffi ATTORNEY Nov. 13, 1934. 1. H. CRABTREE CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, 1929 6 Sheets-Sheet 5 QWEQWW INVENTOR lvoRY H CRABTREE ATTORNEY NOV. 13, 1934. H. CRABTREE 1,980,167

CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES Filed Oct. 16, 1929 6 Sheets-Sheet 6 ija/ INVENTOR 1/0,? 5. fiaqamff ATTORNEY Patented Nov. 13, 1934 UNITED STATES CHANGEOVER MECHANISM FOR MOTION PICTURE MACHINES I Ivory H. Crabtree, Toppenish, Wash., assignor I of three-fourths to Lottie P. Crabtree, Toppenish, Wash.

Application October 16, 1929, Serial No. 399,949

8 Claims. (01. 88-17) This invention relates to automatic control mechanism for motion picture projecting machines where such machines are used in dup1i-,- cate and operate alternately, and it refers particularly to mechanism for changing over from the operating machine 'to the idle machine at the end of a reel of film so as to provide continuous and uninterrupted projection.

The principal object of the present invention 1w is to provide a mechanism that is automatic in its changeover; which operates to start the idle machine when the film in the operating machine is nearly run out, and then, after the started machine has attained proper speed, simultaneously to open its dowserand to close that of the [other machine.

It is also an object in one arrangement of the invention, to provide means operating automatically to energize a signal device to'give the operator warning of the approach of the end of a film and to give ample time for manually closing the arc of the idle machine. In another embodiment, I provide for automatically closing the arc.

A further object of the invention is to provide novel switch mechanisms in connection with the unwinding of the film from the supply reel for controlling the buzzer or are switch closing circuits and also the change over circuits from one machine to another.

Other objects of the invention reside in the provision of manual or push button switches for use when desired in lieu of the automatic means for controlling the change over devices.

Other objects of the invention reside in the details of construgion and combination of parts, as will hereinafter be described.

In accomplishing these objects, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein- Figure 1 is a diagrammatic illustration of the entire change-over system, showing the various circuit connections between the reel switches, motors, solenoids and manual control apparatus. Figure 2 is a diagram of what is termed the buzzer circuit.

cuits.

Figure 4 is a diagram-of the dowser reversing and control circuits.

cally striking the arc of the idle machine to be used in lieu of the manual control.

Figure 6 is a sectional view through a reel and electrodes E and E.

Figure 3 is a diagram of the motor control cirmagazine therefor, particularly illustrating theautomatic switch mechanisms contained-within the reel.

Figure 7 is a horizontal section taken on the line 7-7 in Figure 6.

Figure 8 is a side view of the trigger frame on the reel.

Figure 9 is a cross section on the line 9-9 in Figure 6.

Figure 10 is a front view of the signal switch.

Figure 11 is a front view of the dowser, partly broken away for better illustration.

Figure 11a is a section on line Ila-41a of Figure 1 1.

Figure 12 is a back view of the dowser.

Referring more in detail to the drawings- P and P as shown in Figure. 1, respectively, designate the picture projecting machines which, in use; would be arranged side byside within a projection room. These machines are operated by separate electric motors M and M and light for the projectors is provided by passing an electric circuit through the arc electrodes E'-E' of the machine P and E E of the machine P A. direct current circuit for the arcs flows through 30 the wires 1 and 2 which have connection, by means of wires 3 and 4, with the arc electrodes EE' and, by means of 'wires 5 and 6, with The are circuit for projector P is under control of a manually movable 5 switch lever 7 interposed on wire 4 and adapted to be thrown into and from closed relation with contacts 8. Likewise, the arc circuit of the projector P is under control of a similarly operated switch lever 9 interposed in wire 5 and movable from and against contactslO to break or close the circuit. a

Each projecting machine in this instance embodies the usual projector magazine 11, an upper reel 12 on which the film strip is carried and a lower reel 13 onto which it is wound; it being understood that this winding of the film from one reel to the other is done by means of the usual driving connection with the machine motor. Also, in accordance with the present invention, there is associated with each machine, a do'wser mechanism, later to be described in detail, including a shutter that is movable from and across the line of light projection for cutting off the beam of light to the projection screen; these shutters of the two associated machines being so Figure 5 is a diagram of a circuit for automati-.

actuated that, unless otherwise manipulated, opening of either one is simultaneous with clos-v ing'of the other. The present invention also contemplates use of the governor mechanism with which each projection machine is already equipped, for controlling certain switches which close and open the dowser circuits; the particular governor mechanisms used are not described or illustrated in detail in the present invention, but are diagrammatically designated at 18g in Figures 1 and 4, and are connected to their switches by linkage as at 19. Without going into a detailed description, it is thought suflicient to say that, when a machine attains its proper operating speed, its governor will have spread sufiiciently to actuate the switch'associated therewith to close a circuit through the dowser actuating mechanisms. Mercury switches suitable for this purpose have been diagrammatically illustrated in Figures 1 and 4 wherein 20 and 20 designate the pivotally mounted mercury tubes each having operative connection through a suitable linkage v 19 with its governor and adapted to be tilted upwardly or downwardly in accordance with the governor speed to open or close the circuit between the switch contacts at the ends of the mercury tube.

It is to be understood that the specific type of switch employed and mechanism for opening and closing it is immaterial so long as it will operate satisfactorily and it is to be understood also that these switches are open except when their respective machines are up to operating speed.

The dowser mechanism, as employed with each of the machines, is shown best in Figures 10, 11 and 12. This mechanism, in each instance, comprises a housing 25 adapted to be fixed to the machine magazine at a suitable point and from which a guide frame 26 is rigidly suspended. The guide has an opening 27 alined with the projection lenses and through which the light beam in passing from the machine to the screen is projected. A shutter 28 is adjustable in the guide across this opening to cut off or to permit the light beam to pass to the screen. The shutter in each instance is actuated from and across the opening 27 by means of a connecting link 29 having one end pivotally attached thereto and its other end connected to an arm 30 of a bell crank 31 that is pivotally mounted by a pivot 32 on the back side of the housing 25. Mounted within the housing 25 are paired solenoids with a sliding core bar 34 common to both. From this bar 34, a pin 35 extends rearwardly through a longitudinal slot in the housing wall and into a longitudinal slot 36 in the arm 37 of the bell crank 31. This arrangement of the arm is such that longitudinal shifting of the core bar in opposite directions,

incident to energizing one or the other of the solenoids, will, through the pin and slot connection, eifect pivotal movement of the bell crank and a resultant opening or closing movement of the shutter that is connected therewith. To make the shutter action quick and positive a tensioned spring 40 is attached at one end of the housing and at its other end to the bell crank arm 30. Movement of the crank in closing or opening the shutter causes the axial line of the spring to pass from one side to the other of the dead center line through the pivot 32 and thereby causes a quick, snapping action of the shutter to one or the other of its limits, prevents rebounds and holds the shutter closed or open. In Figures 1 and 4, for better understanding, the dowser shutter of the projector P is designated by character 28a and that for projector P by character 28b, also in these figures, the dowser solenoids for projector P are designated by S and S and those for projector P are designated by and. 5

In accordance with this invention, I also provide the reels on which the film strips are wound with automatic switches through which circuits may be established to sound an alarm for warning the operator that the film on the reel is about to become exhausted or as in the modification of Figure 5, later described, to strike the arc of the idle machine. Other switches automatically operate for closing the circuit to the motor of the idle machine to start the latter; the governor of the started machine, after the machine has attained proper speed, operating to close a circuit to the proper solenoids for opening the dowser shutter of the started machine and simultaneously closing the dowser of the operating machine.

A reel 12, embodying switches according to the present invention, has been illustrated in Figures 6 and 9. In these figures, 45 designates the reel magazine and 46 the reel hub which carries the side flanges 47-47 between which the film strip, designated at 48, is wound. The magazine is stationary and the reel is supported by the end portion of a tubular shaft 50 to revolve within the magazine, the shaft 50 being revolubly contained in an axial bearing 51 formed by the magazine supporting bracket 52. Fastened to one side of the reel, is a frame 54 on which triggers 55 and 56 are pivotally mounted, as at 57, in a manner which permits each of the triggers to be disposed parallel with the hub axis between successive layers of film that are wound on the reel. As here shown, the trigger 56 is disposed closer to the hub of the wheel than the trigger 55; this being in orderthat the trigger 56 will operate at 119 some time later than the trigger 55, in practice about 15 seconds later.

At their outer ends, the triggers are pivotally connected, respectively, with push rods 58 and 59 which extend radially of a reel and through a suitable guide 60 adjacent the hubportion and, at their inner ends, they bear against the ends of rocker pawls 61 and 62. These pawls are pivotally mounted in a collar 63 that is fixed on the tubular shaft and they'have their inner end portions disposed against the ends of contracter rods 64 and 65 which are slidably contained within the shaft and extend lengthwise and from the end of the shaft, as. is shown in Figure 6. Coiled springs 66 and 67 are attached to the push rods 58 and 59 and to the hub of the reel in such manner as to pull inwardly on the rods; the arrangement being such that, with the triggers disposed between layers of the film wound on the reel, the rods will be held at their outward limit against tension of the springs, but when the film unwinds and releases the triggers, the latter will swing outwardly and the rods will be pulled inwardly to thereby rock their respective pawls to shift the contracter rods lengthwise with the shaft. The inner ends of the contracter rods, asshown in Figure '7, are reduced and are slidable through a plug 69 that is fitted in the end of the shaft 50, and springs 70 and 71 are disposed about the reduced portions of the rods to bear against the plug and against shoulders formed on the rods to thereby retain the rods in contact with their respective pawls.

Fixed on the axle portion of the bracket 52, see

Figures 6 and 7, is a yoke 73 which, at its end, 145

cuits presently described. Yieldable plates '78 and r '79- are carried by the posts '76 and 7'7 and these are adapted to be pressed into circuit closing contact with plates 80 and 81 carried, respectively, by the posts 76' and '77 by means of the contracter' rods 64 and 65 on release of the triggers. The plates 78 and 79 in this arrangement serve as circuit control switches and, in the diagrammatic view of Figures 1, 2, 3 and 5, these switches, for the reel of projector P are designated at 78c and 79a and, for the projector P they are designated at 781) and 79b; the switches 78a and 78b being those which are under control of the outer triggers and close their circuits on unwinding of the film from a reel prior to the closing of the switches 79a and 79b.

Associated with the reel switches, as in Figures 1 and 2 is an electrically operated buzzer 85. This is connected by wires 86 and 8'7 with a transformer 88 and the transformer is connected, as presently described, with what is termed the buzzer circuit. This circuit, as shown in Figures 1 and 2, includes switches 89 and 90 which are associated, respectively, with the switch levers '7 and 9 of the arc circuits and their relationship is such that manual adjustment of either lever 7 or 9 from open to circuit closing position permits an automatic opening of its corresponding switch 89 or 90, and likewise adjustment of either lever to open its arc circuit efiects the closing of the corresponding switch 89 or 90.

Electric circuit for the control system and motors is supplied by wires A and B from any suitable circuit, which might be the usual house lighting circuit. The circuit of motor M flows from wire A through wire 100 to one side of the motor and returns through a wire 101 from the other side of the motor to a contact 102 that is adapted to be connected through a solenoid actuated switch lever 103 with the circuit wire B. Current for the motor M flows from the wire A through a wire 105 to one side of the motor and returns through a wire 106 to a contact 107 adapted also to be connected through the switch lever 103 to wire B. The switch lever 103 as shown in Figure 3, has permanent electrical connection with the wire B and is pivotally mounted so as to permit its being shifted by mechanism operating under control of switches 79a and 79b to direct the current through one or the other of the motors.

This control mechanism as shown in Figures 1 and 3, comprises a pair of solenoids 108 and 109. These have a sliding core bar 110 common to both and the core, incident to its movement in opposite directions, operates through a cross bar 111 having pin and slot connections, as at 111 to swing the lever 103 between the contacts 102 and 107 and also to swing a similar, pivotally mounted switch arm 112 between fixed contacts 113 and 114; lever 112 also being electrically connected with wire B. The solenoids, 108 and 109, are operable under control of the reel switches 79a and 79b, and their function is to throw the switch arms 103 and 112 so as to cut in the circuit of an idle motor incident to the closing of the reel switch of the operating projector. To accomplish this result, see -Figure 3, the switch 79a is connected at one side by wire 118 to the wire A. The other side of the switch 79a is connected by a wire 119 with the outer end pole of the solenoid 109. Likewise, one side of switch 79b is connected by a wire 120 with the wire A and its other side is connected by a wire 121 with the outer end pole of the solenoid 108. The

inner pole of this latter solenoid is connected by a wire 122 with the contact 114. Likewise, the inner pole of the solenoid 109 is connected by a wire 124 with the contact 113.

The buzzer control circuit, see Figure 2, consists of a connection through wires 11B and 130 from wire A to one side of switch 781:. and a similar connection through wires 120 and 131 to one side of switch 78b. The other pole of switch 78a is connected by wire 132 with the outside pole of switch 90, which in turn has its inner pole connected by a wire 133 with the inner pole of the switch 89 and this, in turn, has its outer pole connected by a wire 134 with the other pole of switch 78b. The transformer 88, which is under control of the buzzer circuit, is connected by wires 135 and 136, respectively, with wire 133 and wire B.

Now, assuming the projector P and motor M to be in operation, with switches 78b and 79b and 90 open; and assuming projector P and motor M to be idle but ready to start with switches 78a, 7911 open and switch 89 held closed by switch lever 7 as in Figure 1; the motor circuit flows to motor M from wire A, see Figure 3, through wire 105 and returns through wire 106, contact 107, switch lever 103, to wire B. As the film strip unwinds from reel 12 of projector P it finally permits closing of switch 78?). This closes a circuit tothe transformer for energizing 'the buzzer; the circuit passing from wire A, see Figure 2, through wires 120, 131, switch 78b, wire 134, switch 89, wires 133 and 135 to the transformer 88 and through wire 136 to wire B. This causes the buzzer to be energized and receiving the buzzer signal, the operator immediately strikes the arc of projector P by throwing the switch lever 7 over against contact 8, and this permits opening of the switch 89 and thus opens the buzzer circuit.

Following the closing of the buzzer signal switch 7812, there is a continued unwinding of film from reel 12 and preferably, after about fifteen seconds, the switch 79b is closed. This causes current to be directed through solenoid 108, see Figure 3, to momentarily energize it and shift core bar 110 to thereby throw the switch arms 103 and 112 'to their opposite positions against contacts 102 and 113 as in dotted lines in Figures 1 and 3, to close the circuit through motor M to start operation on projector P On closing of switch 79b, current flows from wire A,

through wires 120, switch 791), wire 121, solenoid 108, wires 122, contact 114, arm 112, to wire B. This completes the circuit, energizes the solenoid 108 and causes bar 110 to shift to the left and, in so doing, to throw the levers 103 and 112 against the contacts 102 and 113; this being done by mechanism shown in Figures 1 and 3. Our: rent then fiows to motor M from wire A through wire 100, and returns through wire 101, contact 102 and lever 103 to wire B.

In order that this operation of the solenoid may not cutoff motor M since it is desired that it continue to operate for a short time to run out 1 141 to wire B. After the tail end of the film of projector P has been run out, then the motor M is manually cut out by throwing switch lever 140 so that it breaks connection .with contact 142 It is then engaged with contact 142 to be ready for the changeover from motor M back to motor M When the machine P is stopped, the arc switch lever 9 is opened to cut ofi the circuit to the electrodes E and E while the machine is idle.

The sounding or a buzzer signal and a following changeover from motor M back to motor M would be accomplished in a similar way to switches 78a and 79a in the reel 12 of projector P In the instance of the buzzer signal being closed by releaseof switch 78a, the signal woiild be cut off by the operator throwing the lever 9 to close the circuit to electrodes of projector P The motor circuit for M would subsequently be cut in by the closing of switch 79a which causes a momentary energizing of solenoid 109 to throw switch levers 103 and 112 back into' the contacts 107 and 114. Cutting out of the circuit to motor M after running out of the film, is accomplished by reversing switch lever 140 to open the connection with contact 142.

The dowser shutters 28a and 28b are operated by circuits under control of the speed governors 18g on the projectors P and P and the closing of the shutter of one machine and the simultaneous opening of the dowser of the other machine is occasioned by the started machine attaining its proper operating speed which closes its switch The dowser control circuits are shown best in Figure 4, and are as follows: One pole of the solenoid S is connected to wire A by wires 150 and 118. Likewise, one pole of the solenoid S is connected to wire A by wires 151 and 120. A wire 152 connects together the remaining poles of solenoids S and S A wire 153 connects corresponding poles of solenoids S and S and their other poles are connected to wire A by wires 1541l'8 and 155-120 respectively. The core bar 34a of solenoids S and S which actuates the shutter 28a also actuates a mercury switch 160 to open and close a circuit that is provided between the switch 20a. and the outer pole of solenoid S through wires 161 and 162; this switch 160 being closed when the shutter is closed. Likewise the core bar 34b of solenoids S and S which actuates the shutter 28b operates a mercury switch 163 to open and close a circuit connection provided between switch 20b and the outer pole of solenoid S 'through wires 164 and 165; this switch 163 also being closed and opened in accordance with closing and opening of the shutter 28b. The switch 20a as shown in Figure 4, is connected at one side to the contact 113 by a wire 166, and the switch 28b is connected to the contact 114 by a wire 167.

Assuming the dowsers and their circuits to be so arranged, and the dowser shutter .of the operating projector P to be open and that of the idle projector P to be closed, also assuming that switches 20b, 160 and 163 are closed; when the switch 79b closes by reason of its being released by the unwinding of film in the reel 12 of projector P a circuit will be closed as previously described which will cause the solenoid 108 to be energized and to thereby reverse the switch levers 103 and 112 to close a circuit through the motor M to start the latter. Motor M continues to operate by reason of the circuit connection pro vided through the switch 139; As soon as the projector P attains the proper speed its governor mechanism 18g closes'the mercury switch 20a to thereby close the dowser circuit of that machine and to open the dowser; the current passing from wire A through wires 118, 150, solenoid S wire 162, switch 160, wire 161, switch 20a, wire 166, contact 113, lever 112 to the wire B. This causes solenoid S to be energized to shifting the bar 3411 to thereby raise the dowser shutter 28a, to open position. Simultaneous with this operation, current passes from wire A through wires 120, 151, solenoid 8*, wire 152, wire that above described, incident to closing of 162, switch 160, wire 161, switch 20a, wire 166,

contact 113, lever 112 to the wire B thereby energizing solenoid S to move the core' bar 34?)" to close the dowser shutter of projector P The movement of core 34a opens the switch 160 and movement of 34b closes the switch 163; then later on when a changeover is made from projector P back to the projector P closing of switch 20b causes current to flow from wire A to solenoids S and S through the connections provided and back to the wire B, thereby causing the solenoid to be energized, and the core bars shifted to close the dowser shutter 28a and to open the dowser shutter 28b.

As a manual control for the changeover system for use independent of the automatic mechanism, I provide a three point switch 170, see Figure 4, having contacts 1'71, and 172 connected respectively by wires 173 and 1'74 with the wires 166 and 167 which lead to the contacts 113 and 114. 'The switch lever 1'76 connects by wire 177 to a switch 178 whereby connection may be made with wire B simultaneous with the cutting ofi of circuit from wire B to switch levers 103 and 112. By pressing the lever 176 into contact with one or the other of the contacts 171 or 172 a circuit may be closed to the wire B without its passing through the automatic control and regardless of the position of the levers 103 and 112.

For instance should it be desired to use the automatic dowser control without using the automatic changeover from one motor to another the operator may start one or the other motor manually, as presently described, and press the switch lever 176 against the corresponding contact 171 or 172; then when the started motor has attained its proper operating speed, its switch 20a or 20b will beclosed and this, as previously described, will close the dowser control circuit'to efiectthe opening of its shutter and the closing of the shutter of the other machine.

In connection with the motor circuits as shown in Figure 3 Ihave provided for manually effecting a changeover from one motor .to the other devices. This comprises a three point switch 190 having contacts 191, and 192 connected with the wires 193 and 194 connected with the wires 119 and 121 respectively. The switch lever 195 is connected by wire 196 with wire 120. Should itbe desired to change over from one motor to the other the operator presses on the lever 195 to close it against contact 191 or 192 dependent upon the motor that is to be started. This would close the solenoid circuit the same as if the circuit had been. closed by the switch 79a or 791).

Since it is important, attention is directed to the fact that the connections 166 and 167, which lead from the switches 20a and 20b for the purpose of connecting these. switches to the circuit wire B, lead to the contacts 113 and 114 and do not connect with the wire B through the contacts 102 and 103 which would be the more direct me c? connection. The purpose of extending these connections to the lower contacts is to avoid flickering of the shutters after a changeover is made. It is quite apparent if wires 166 and 167 extended to contacts 102 and 103, respectively, a changeover from one machine to the other would result in a reciprocating action of the core bars 34a. The method of connecting, as shown in Figure 4, overcomes this possibility.

In some instances, it may be desirable to employ an automatic means for striking the arc of the machine to be started. In Figure 5, I have illustrated diagrammatically a circuit and devices for effecting this automatic closingof the arc switches 7 and 9. In this arrangement switch lever 7 is moved from open to closed position by shifting of the core 196 or a solenoid 197, and the switch lever 9-is likewise actuated by a core 198 of a solenoid 199. The switch 78a is connected at oneside to the wire A through a wire 200, and it is connected at ,the other side by a wire 201 to one pole of the solenoid 199, the othef'pole of the solenoid being connected by a wire 202 to the wire B. Likewise, one side of the switch 781) is connected to the wire A by a wire 204 and its other side connects by wire 205 with one side of solenoid 197. The other side of the solenoid connects to wire B through a wire 208.

In this above arrangement when switch 781) "closes incident to unwinding of film from the reel 12 in the projector P a circuit will be closed through the solenoid 197 to close the switch '7 to thereby strike the arc of the projector P Like: wise, when switch 78a closes, a circuit is closed through the solenoid 199 to close the switch 9 to strike the arc of the projector P Opening of these switches is manual andwould be done at the same time that the motor for the operating machine is shut down.

By using the above-described circuits anddevices it is readily apparent that an automatic operation is effected whereby the operator of machines is first warned of the approach of the end of the film strips so that he maystrike the arc of the idle machine in plenty of time for it to be properly heated when the machine is set in operation. Following this automatic operation of the various switch devices placed to start the idle machine, and after it has attained proper speed to simultaneously open its shutter mechanism and to close that of the operating machine.

Having thus described my invention, what I claim as'new therein and desire tosecure by Letters Patent, is:

1. In combination with two motion picture machines arranged for alternate operation and each embodying a film feed reel and an operating motor, a main circuit, a normal operating circuit for each motor, an electrically actuated changeover mechanism connected in the main circuit and operable to deliver current to one or the other of said motors, said changeover mechanism com-- prising a pair of spaced contacts connected, respectively, with the two motors, a switch arm movable from one" contact to the other to cause current to flow through one or the other of the motors, a pair of solenoids operatively connected for moving the switch arm, circuits for the solenoids associated, respectively, with the film feed reels of the two machines and each including a switch operable incident to unwinding of a predetermined amount of film from the operating machine to close its circuit to actuate the switch arm-to close a circuit through the motor of the idle machine and to open the normal operating circuit to the motor of the operating machine, a second switch actuated by the solenoids simultaneous with the movement of the switch arm, thereby to open the circuit of the energized solenoid.

2. A device as in claim 1 wherein shunt connections 'are provided from the said contacts across the switch arm of the changeover mechanism and a manually operable switch is interposed in said shunt connections through which circuit connection may be made or opened with either of said motors independent of the changeover mechanism.

3. In combination with two motion picture machines arranged for alternate operation and each including a mm feed reel and an operating motor, an electric circuit for the motors having direct connection with one side of each motor, a changeover mechanism comprising a pair of spaced con tacts having circuit connections, respectively, with the othersides of the motors, a switch arm connected with said other side of the circuit and movable from one contact to the other, a pair of solenoids, a core bar for the solenoids connected to move the switch arm, circuits for the solenoids including switches associated, respectively, with film feed reels and each operable incident to the unwinding of a predetermined amount of film to close the circuit of its solenoid to move the switch arm to thereby close a circuit through ,the'motor of the idle machine and to open the circuit of the motor of the operating machine, and a second switch arm common to both the solenoid, circuits and movable by the core bar, to open the circuit of the energized solenoid.

4. The combination with two motion picture machines arranged for alternate operation and each including a film reed reel, an arc circuit and a switch for controlling its arc circuit, of a signal circuit associated with each of the machines and each rendered operative by the opening of the arc circuit switch of the opposite machine and each including a normally open switch associated with the film feed reel operable incident to the unwinding of a predetermined amountof film, to automatically close the circuit to the signal.

5. The combination with two motion picture machines arranged for alternate operation and each embodying a film feed reel, an arc circuit and a switch element movable to open or close the arc circuit, of a signal circuit associated with each machine and each including a normally open switch that is automatically operable, incident to the unwinding of a predetermined amount of film from the film feed reel to close the signal circuit and a second switch which is designed to be held closed by the open switch element in the arc circuit of the idle machine and adapted to open incident to adjustment of this element for closing its arc circuit. I

6. In combination with two motion picture machines, each cornprising a film feed reel, an operating motor, a governor device and a shutter movable from and across its line of projection, an electric circuit for the motors, a changeover mechanism for directing current to one or the other of said motors, control means for the changeover mechanism including switches associated with the feed reels and operable incident to unwinding of a predetermined amount of film to start the motor of the idle machine, electric actuating devices for each shutter to move it between open and closed positions, electric cirsaid circuits operable by the said governor device of the started machine to close the circuit to simultaneously cause opening of the shutter of the started machine and closing of the shutter of the other, and other switches in the circuits movable by the shutter actuating devices to open the circuits after'reversal of the shutters.

7. In a system of the character described, embodying a plurality of control circuits, a reel supporting bracket having a hub portion, switch mounting means fixed to the bracket, a tubular shaft rotatably mounted in the hub and extended at one end to the switch mounting means, a film reel mounted on the other end of the shaft, a. trigger frame fixed to the reel, spring actuated triggers fixed to the frame and adapted to be held in set position by the film strip wound on the reel and to be released by the removal of a predetermined amount of film therefrom, switches mounted by said switch mounting means and connected in said control circuits, push rods for closing the switches extended thereto through the said tubular shaft and having operative connection with the said triggers.

8. A device as in claim 7 wherein bell cranks are mounted on the tubular shaft and operatively engage the push rods and have operative connection with the triggers, and where shoulders are formed on the push rods and springs bear against said shoulders for yieldably retaining the push rods in retracted position.

IVORY H. CRABTREE' 

